Best settings for cutting 3/4" MDF rectangles

[denver]

Hello,

I was asked recently about cutting a large number of sign blanks from 3/4" MDF - 72 per sheet. So each is approximately 4" x 16", less the cutter diameter. The sample I have is 1/4" less, so it was probably cut with a 1/4" bit. Each blank also has a small pocket cut into it. Does anybody have recommendations for a starting point regarding type of cutter, feed rate, etc? I would like to be able to cut these in a minimum amount of time of course, and with a minimum of additional cleanup work as well.

I have a 2.2 HP HSD spindle, and when I've cut 3/4" MDF in the past with a 1/4" bit I've usually done it in two passes, and usually around 3 IPS. I looked around here and found some older accounts of people cutting straight lines at full depth and fairly high feed rates. So I was wondering if there's anything new on the subject.


Thanks,

Denver

[beacon14]

Much depends on your holddown method. Instead of getting into a longwinded answer with a lot of generalities, please describe your hold down abilities for a more specific response.

[knight_toolworks]

yes the hold down is critical you could do it with a couple of feins. if you use a downcut bit you could do it in one pass at 3ips. the sawdust would keep the pieces from moving.

[jhicks]

Larger the bit, the more the lateral torque so try to dial in smallest bit with fastest speed and fewest passes but hold down is key. Maybe tabs or bridges will help or an onion skin for final pass works well.
I would give the estimate at a slow speed and max passes, then get order and improve internally to best rate for finished edges and what you need to end up with.
MDF does wear on those bits so make sure you consider bit costs as well.